Hi,
just wondering: Looking at the AWR geometry, the "width" of the substrate is much smaller then the hight. Therefore the GND is pretty far away from the meander. How is the nearby boundary (left and right from the meander) handeled in Sonnet and EMSight. "Open" or "electric"? Since both programs are MoM codes, they might(?) not care about the small substrate size. HFSS is a FEM code at it DOES care if the calcualtion box is to small. Maybe this explains the difference.
F.